Do not talk about "statements" (exercism#740)

Author: angelikatyborska

concepts/case/introduction.md

@@ -1,6 +1,6 @@
 # Introduction
 
-`case` is a control flow structure that allows us to compare a given value against many patterns. Clauses in a `case` statement are evaluated from top to bottom, until a match is found.
+`case` is a control flow structure that allows us to compare a given value against many patterns. Clauses in a `case` expression are evaluated from top to bottom, until a match is found.
 
 ```elixir
 age = 15

exercises/concept/german-sysadmin/.docs/introduction.md

@@ -44,7 +44,7 @@ The longer the first list is, the slower the concatenation, so avoid repeatedly
 
 ## Case
 
-`case` is a control flow structure that allows us to compare a given value against many patterns. Clauses in a `case` statement are evaluated from top to bottom, until a match is found.
+`case` is a control flow structure that allows us to compare a given value against many patterns. Clauses in a `case` expression are evaluated from top to bottom, until a match is found.
 
 ```elixir
 age = 15